Belt retractor

ABSTRACT

A belt retractor for an occupant restraining system in vehicles is provided with a belt drum (12) rotatably mounted in a frame (10) and acted upon by a wind-up spring, a locking mechanism for the belt drum and able to be activated by the pivoting, caused in a manner responsive to the vehicle and/or the belt webbing, of at least one actuator pawl (20a; 24), and catch elements (32, 34; 50, 62) pivotally mounted on the belt drum (12) and able to rotate in relation it, said catch elements (32, 34; 50, 62) and the actuator pawl (20a; 24) being able to assume, by rotation of the belt drum (12) in the windup direction, a first position in relation to each other in which the catch elements (32, 34; 50, 62) engage the actuator pawl (20a; 24) and prevent pivoting thereof, and by rotation in the unwinding direction a second position, in which the catch elements (32, 34; 50, 62) clear the actuator pawl (20a; 24). For the transition from the first position to the second one rotation of the belt drum (12) through a predetermined angular movement of at least approximately 10° is necessary. This prevents any undesired locking of the belt drum on taking up the belt webbing in a reliable, safe fashion.

The invention relates to a belt retractor for an occupant restrainingsystem in vehicles comprising a belt drum rotatably mounted in a frameand acted upon by a wind-up spring, a locking mechanism for the beltdrum and adapted to be activated by the pivoting, caused in a mannerresponsive to the vehicle and/or the belt webbing, of at least oneactuator pawl, and catch elements pivotally mounted on the belt drum andable to rotate in relation to the drum, said catch elements and theactuator pawl being able to assume, by rotation of the belt drum in thewind-up direction, a first position in relation to each other in whichthe catch elements engage the actuator pawl and prevent pivotingthereof, and by rotation in the unwinding direction a second position,in which the catch elements clear the actuator pawl.

In such a belt retractor an unintended locking of the belt drum mayoccur, if the retraction operation is abruptly terminated, for examplebecause the male lug of the safety belt strikes an obstruction orcatches in the belt diverter fitting, or if the termination of theretraction operation coincides with vibration of the belt retractor, asfor example on folding back a rear seat bench, should the belt retractorbe mounted adjacent to the rear luggage space of a vehicle. In suchcases owing to sharp deceleration of the belt drum locking of the drumwill be caused in a manner sensitive to the belt webbing, or owing tovibration in the drum, in a manner sensitive to the vehicle with theresult that later draw off of belt webbing is prevented.

Various different measures have already been proposed to avoid suchundesired locking. Such measures do however involve relatively highcosts of manufacture and assembly; nevertheless in the case of aparticularly sudden termination of the wind-up movement of the belt drumor in the case of heavy vibration of the belt retractor it is impossibleto prevent locking thereof reliably.

The present invention is to provide a belt retractor, in the case ofwhich such undesired locking is prevented using simple means, a smallnumber of additional components and without adjustment after assembly.In the belt retractor of the invention a rotation of the belt drumthrough a predetermined angular range of at least approximately 10° isnecessary for the transition from the first into the second position.This ensures that even in the case of an abrupt termination of thewind-up movement of the belt webbing or in the case of powerfulvibration or shaking of the belt retractor unintended locking of thebelt drum is reliably prevented. The avoidance of locking of the beltdrum for the predetermined angular movement is without any effect on theproper functioning of the belt retractor, since in the case of anoptimum setting of the belt retractor as well the belt drum must performa certain degree of rotation for initiation of locking thereof in amanner responsive to the belt webbing or to the vehicle.

Preferably there is a provision such that the predetermined angularmovement lies between approximately 20° and approximately 25°.

In the case of one possible embodiment of the invention there is theprovision that the actuator pawl is pivotally mounted on one side of thebelt drum and may be brought into engagement with internal tooth meansof an activating ring, which is rotatably mounted on the frame, by meansof a control cam, which is formed on a control disk, which is mounted onthe belt drum for limited rotation, that the actuator pawl possesses ahead and that the catch elements comprise a brake disk rotatably mountedon the belt drum, which brake disk is retarded by friction between itand the frame and possesses a catch part, which in a first positionengages the head and in the second position releases same. Thecomponents called for in addition to those necessary for a conventionalbelt retractor, namely the brake disk and the friction element, may bereadily integrated in already existing systems and hardly cause anyadditional costs. Since the frictional force required for braking thebrake disk is very low, rotation of the belt drum is hardly obstructedso that the effect on the force necessary for unwinding and retractionis negligible.

In accordance with a preferred development of the preceding embodimentof the invention it is possible to provide a design such that the catchelements furthermore comprise a pivotally mounted catch lever which isfictionally coupled with the belt drum and is mounted for limitedpivoting around the axis thereof, such lever being provided with acircularly arcuate abutment surface, which extends over a range equal tothe angular movement and which in the first position engages an actuatorpawl of an inertial sensor and in the second position releases same. Ontaking up belt webbing such a belt retractor ensures that neither theactuator pawl of the locking mechanism nor the combined inertial sensorand actuator pawl may pivot into engagement with the tooth meansassociated with them. If there is an action only applied to the actuatorpawl of the locking mechanism and the pivoting thereof is prevented,there may, if the belt retractor is heavily shaken, nevertheless be anengagement of a combined inertial sensor and actuator pawl with theexternal tooth means of the control wheel with the result that unwindingof belt webbing from the belt drum is obstructed. For reliable avoidanceof undesired locking of the belt drum pivoting both of the actuator pawlof the locking mechanism and also of the combined inertial sensor andactuator pawl must be forestalled.

Further features and developments of the invention will be understoodfrom the following detailed description in conjunction with thedrawings.

FIG. 1 shows an axial section of part of a belt retractor in accordancewith a first embodiment.

FIG. 2 shows a diagrammatic lateral elevation of the belt retractor ofFIG. 1 in the process of unwinding the belt.

FIG. 3 shows a corresponding lateral elevation with the actuator pawlengaged.

FIG. 4 depicts a corresponding lateral elevation during rotation of thebelt drum of FIG. 1 in the wind-up direction.

FIG. 5 is an axial section of part of a belt retractor in accordancewith a further embodiment.

FIG. 6 is a diagrammatic lateral elevation of the belt retractor of FIG.5 with the actuator pawls locked.

FIG. 7 shows a diagrammatic lateral elevation of the belt retractor ofFIG. 5 in a transitional state.

FIG. 8 is a diagrammatic side view of the belt retractor of FIG. 5 withthe actuator pawls released.

In FIGS. 1 through 4 the reader will be able to see one belt retractorin accordance with a first embodiment of the invention. In suchretractor a belt drum 12 is rotatably mounted in a load bearing frame10. Within a protective cap 14 mounted on one side of the frame 10 acontrol mechanism sensitive to the vehicle and to the belt isaccommodated for the catch system (not illustrated) of the beltretractor. On the opposite side of the belt retractor a wind-up spring(not illustrated) is arranged in a conventional fashion.

The control mechanism comprises an externally toothed control disk 16,which is mounted in a rotatable manner on the belt drum 12 by means of abearing pin 18. An inertial sensor 20 cooperates with the external toothmeans of the control disk 16, such sensor being conventionallyconstituted by an inertial ball and a pivotally mounted combinedinertial sensor and actuator pawl 20a to be moved into engagement withthe external tooth means on the control disk 16 by the inertial ball. Ona bearing plate 22, which is connected with the belt drum 12 in such amanner as to prevent relative rotation an actuator pawl 24 is pivotallymounted by means of a bearing pin 26. In order to increase the inertiaof the disk 16, which is made of plastic, an inertial disk 28 of ametallic material is coupled in such a manner as to prevent relativerotation. This inertial disk 28 is provided with a control cam 28a,cooperating with an actuator pawl 24 and, when there is a relativerotation between the belt drum and the control disk 16, thrusts againsta radial spur 24a on the actuator pawl 24 with the result that the tipof same is pivoted outward as shown in FIG. 3. In this condition it willengage internal tooth means in an activating ring 30, which surroundsthe bearing plate 22 and is rotatably mounted in the frame 10. Theactivating ring 30 is provided with a radial arm 30a, which is supportedby a compression spring 31 on the frame 10. By rotation of theactivating ring 30 the catch pawl of the catch system (not illustrated)is brought into its operating position in a conventional manner.

By means of the bearing pin 18 a brake disk 32 is furthermore rotatablymounted on the side of the belt drum 12. The brake disk 32 is providedwith a catch element 34 extending perpendicularly toward the bearingplate 22, such catch element 34 being formed by a narrow wall partextending in an arcuate fashion on the external periphery of the brakedisk 32 for an angle of a few degrees. A friction ring 36 is fittedabout the external periphery of the brake disk 32 and has a grooveformed in its outer periphery. A spring ring 38 is received in thisgroove and thrusts the friction ring 36 with moderate force against theouter periphery of the brake disk 32. The friction ring 36 is providedwith a U-shaped holding part 36a held on a laterally projecting lug 10aon the frame 10 so that the friction ring 36 is held in such a manner asto prevent relative rotation and owing to frictional engagement with thebrake disk 32 brakes rotation thereof. This braking action is howeverdesigned to be so small that the wind-up and unwinding forces on thebelt drum 12 are not substantially affected.

At its end remote from the tip the actuator pawl 24 possesses anelongated head 24b which is gently curved in an arcuate manner. When thebelt drum is turned in the wind-up direction, as shown in FIG. 4, thehead 24b will firstly move toward the catch part 34 and will then moveradially outside of and past it until the said catch part 34 abuts theactuator pawl 24. After this the brake disk 32, which, owing to thefriction produced by the friction ring 36, has so far remainedstationary, will be entrained in rotation and will rotate with the beltdrum until there is a reversal in the direction of rotation. When suchreversal in the direction of rotation takes place, the catch part 34will come clear of the actuator pawl 24 and the brake disk 32 will behalted again by friction. However as long as the catch part 34 is hookedabout the head 24b, i.e. for the predetermined angular movementcorresponding to the extent of the head 24b in the peripheral direction,the actuator pawl 24 will be prevented from pivoting into engagementwith the internal tooth means on the activating ring 30, since the head24b abuts the catch part 34. It is only when after such rotation in theunwinding direction through the predetermined angular movement the catchpart 34 releases the head 24b that the actuator pawl 24 may be pivotedin a manner sensitive to the vehicle or the belt webbing by the controlcam 28a and come into engagement with the internal tooth means of theactivating ring 30, as shown in FIG. 3. The predetermined angularmovement, which must be performed by the belt drum for the actuator pawl24 to be released after being held captive, amounts to at leastapproximately 10° and preferably between approximately 20° andapproximately 25°.

In accordance with a preferred further development, illustrated in FIGS.5 through 8, of the preceding embodiment there is, in addition to thecatch action on the actuator pawl 24 of the locking mechanism on takingup the belt webbing, a catch action effective for the actuator pawl 20aof the inertial sensor 20 responsive to the vehicle. Only the additionalcomponents and their function will be described; the remaining parts arethe same as in the preceding embodiment.

A hub-like bearing part 40 is connected in such a manner as to preventrelative rotation on the bearing pin 18 of the belt drum by the end ofthe bearing pin 18 being press fitted in the concentric hole 42 in thebearing part 40. The bearing part 40 is provided on its outer peripherywith an encircling groove 44, in which two circularly arcuate arms 46and 48 of a catch lever are held which is generally referenced 50. Intheir outer periphery these circularly arcuate arms 46 and 48 for theirpart have a groove 52 into which an annular spring 54 fits whichsurrounds the said circularly arcuate arms 46 and 48. The catch lever 50is provided with two radial arms 56 and 58 which are spaced apart in thecircumferential direction. At their end opposite to the bearing pin 18the radial arms 56 and 58 are connected together by a rib 60 extendingin the peripheral direction and having an engagement surface 62 on theradially outer side, such rib being extended at the end opposite to thearm 56 by a projection 64, which can come into engagement with the lug10a. The engagement surface 62 is arranged at such a distance from thebearing pin 18 that it may come into engagement with the combinedinertial sensor and actuator pawl 20a. At one end of the engagementsurface 62 a head 66 is formed.

In FIG. 6 the catch lever 50 is depicted in the first position onwinding up of the belt webbing. Owing to the frictional engagement ofthe circularly arcuate arms 46 and 48 on the bearing part 40 on rotationof the belt drum 12 the catch lever 50 is turned clockwise in terms ofFIG. 6 until the head 66 of the rib 60 rides onto the tip of thecombined inertial sensor and actuator pawl 20a. In this positionpivoting of the combined inertial sensor and actuator pawl 20a intoengagement with the external tooth means of the control disk 16 isprevented. Simultaneously pivoting of the control lever 24 is prevented,since the catch part 34 engages the head 24b.

FIG. 7 shows a transitional condition of the catch lever 50. Thiscondition occurs after reversal of the direction of the rotation of thebelt drum 12 from the wind-up direction to the unwinding direction andcorresponds to a rotation of the belt drum 12 through the predeterminedangle in the unwinding direction. The combined inertial sensor andactuator pawl is still just held captive by the engagement surface 62,extending for the predetermined angular movement, which in thisembodiment too preferably amounts to between approximately 20° andapproximately 25°. In the event of the belt drum 12 being turned fartherin the unwinding direction, the catch lever 50, starting from theillustrated position, will be turned farther anti-clockwise until thesecond position is reached, in which the projection 64 is in engagementwith the lug 10a and the combined inertial sensor and actuator pawl 20ais released. This is illustrated in FIG. 8. It will be seen that thecatch part 34 has released the head 24b on the actuator pawl 24.

The entire catch lever 50 with the circularly arcuate arms 46 and 48,the radial arms 56 and 58 and the rib 60 constitutes a single plasticcomponent. Each of the circularly arcuate arms 46 and 48 extendspreferably for somewhat less than 180° so that between the two ends ofsuch circularly arcuate arms a gap is left preventing the arms 46 and 48bearing directly against one another. The force of engagement of thecircularly arcuate arms 46 and 48 on the bearing part 40 is thuspredominantly set by the size of the annular spring 54 and on turning ofthe catch lever 50 in relation to the belt drum 12 there will be africtional force only affecting the wind-up and unwinding forcesapplying foe the belt webbing to an insignificant extent.

I claim:
 1. A belt retractor for an occupant restraining system invehicles, comprising:a frame; a belt drum rotatably mounted in theframe; a wind-up spring acting upon the belt drum; a locking mechanismfor the belt drum; at least one pivotable actuator pawl, the lockingmechanism being activated in a manner responsive to the vehicle and/orthe belt webbing by pivoting of the actuator pawl; catch elementspivotally mounted on the belt drum and rotatable relative to the beltdrum, said catch elements and the actuator pawl being able to assume, byrotation of the belt drum in the wind-up direction, a first position inrelation to each other in which the catch elements engage the actuatorpawl and prevent pivoting thereof, and by rotation in the unwindingdirection, a second position in which the catch elements clear theactuator pawl; wherein, for the transition from the first into thesecond position, a rotation of the belt drum through a predeterminedangular range between approximately 20° and approximately 25° isnecessary.
 2. A belt retractor for an occupant restraining system invehicles, comprising:a frame; a belt drum rotatably mounted in theframe; a wind-up spring acting upon the belt drum; a locking mechanismfor the belt drum; at least one pivotable actuator pawl, the lockingmechanism being activated in a manner responsive to the vehicle and/orthe belt webbing by pivoting of the actuator pawl; catch elementspivotally mounted on the belt drum and able to rotate in relation to it,said catch elements and the actuator pawl being able to assume, byrotation of the belt drum in the wind-up direction, a first position inrelation to each other in which the catch elements engage the actuatorpawl and prevent pivoting thereof, and by rotation in the unwindingdirection a second position, in which the catch elements clear theactuator pawl;wherein a rotation of the belt drum through apredetermined angular range of at least approximately 10° is necessaryfor the transition from the first into the second position; anactivating ring with internal tooth elements, rotatably mounted on theframe, and a control disk with a control cam, which is mounted on thebelt drum for limited turning motion, are provided; the actuator pawl ispivotally mounted on one side of the belt drum and may be brought intoengagement with the internal tooth means of the activating ring by meansof the control cam formed on the control disk; the actuator pawlpossesses a head; and the catch elements comprise a brake disk rotatablymounted on the belt drum, the brake disk being retarded by frictionbetween it and the frame and possessing a catch part which in the firstposition engages the head of the actuator pawl and in the secondposition releases the head.
 3. The belt retractor as claimed in claim 2,wherein the catch elements further comprise a catch lever frictionallycoupled with the belt drum and mounted for limited pivoting motion aboutthe axis of the belt drum, the catch lever being provided with acircularly arcuate engagement surface extending for a rangecorresponding to said predetermined angular range and which in the firstposition engages an actuator pawl of an inertial sensor and in thesecond position releases said actuator pawl of said inertial sensor. 4.The belt retractor as claimed in claim 2, wherein the brake disk is ableto be entrained in rotation against a frictional force in relation tothe frame by the actuator pawl riding against the catch part on rotationof the belt drum, the frictional force being negligible as compared withthe force of the wind-up spring.
 5. The belt retractor as claimed inclaim 4, wherein the catch part is constituted by a wall part extendingperpendicularly from the brake disk and, on rotation of the belt drum inthe wind-up direction, the head of the actuator pawl engages radiallyoutwardly behind the wall part.
 6. The belt retractor as claimed inclaim 5, wherein the brake disk has a friction ring fitting about itsouter periphery and the friction ring is held on the frame so as toprevent relative rotation.
 7. The belt retractor as claimed in claim 6,wherein the friction ring is encircled by a spring ring.
 8. The beltretractor as claimed in claim 2, characterized in that the head extendsfor a range corresponding to said predetermined angular range.
 9. A beltretractor for an occupant restraining system in vehicles, comprising:aframe; a belt drum rotatably mounted in the frame; a wind-up springacting upon the belt drum; a locking mechanism for the belt drum; atleast one pivotable actuator pawl, the locking mechanism being activatedin a manner responsive to the vehicle and/or the belt webbing bypivoting of the actuator pawl; catch elements pivotally mounted on thebelt drum and rotatable relative to the belt drum, said catch elementsand the actuator pawl being able to assume, by rotation of the belt drumin the wind-up direction, a first position in relation to each other inwhich the catch elements engage the actuator pawl and prevent pivotingthereof, and by rotation in the unwinding direction, a second positionin which the catch elements clear the actuator pawl;wherein a rotationof the belt drum through a predetermined angular range of at leastapproximately 10° is necessary for the transition from the first intothe second position; an inertial sensor and a control disk with externaltooth means are provided; the actuator pawl is pivotally mounted on theinertial sensor and in a manner responsive to the vehicle, the actuatorpawl being able to be brought into engagement with the external toothmeans on the control disk; the catch elements comprise a catch levercoupled frictionally with the belt drum and able to pivot to a limitedextent about the axis thereof, the catch lever having two circularlyarcuate arms fitting about the periphery of a bearing part which ismounted on the belt drum so as to prevent relative rotation and whichhas the form of a circular disk; the arms are held in frictionalengagement with the peripheral surface of the bearing part by a metallicannular spring encircling the arms; and the catch lever is provided witha circularly arcuate engagement surface extending for a rangecorresponding to said predetermined angular range and which in the firstposition comes into engagement with the actuator pawl and in the secondposition releases the actuator pawl.
 10. The belt retractor as claimedin claim 9, wherein in its outer periphery the bearing part possesses agroove for the circularly arcuate arms to fit into.
 11. The beltretractor as claimed in claim 9, wherein the circularly arcuate armspossess a groove in their outer periphery in which the annular spring isheld.